Improvement in steam geneeatoes



A@uiten gratta attntffit, p A

.less surface than by the modes heretofore suggested. l

THOMAS AND THOMAS H. MITCHELL, OF ALBANY, NEW YORK.

Letters PatentlVo. 64,895, dated .May 21, 1867.

IMPROVEMENT 1N STEAM cENEEAroEs.

TO ALL WHOM IT MAY CONOERN:

Be it known that we, THOMAS MITCHELL and THOMAS H. MITCHELL, of Albany,in the State of New York, have invented certain new and usefulimprovements in-Steam Generators and we do hereby declare that thefollowing is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, making part of thisspecification, in whiclr.v A I Figure 1 is a longitudinal verticalsection; and

Figure 2 a cross vertical section.

The same letters indicate like parts in all the figures.

Qur said invention relates to improvements in that class of steamgenerators in which waterin small quantities is injected and thrown onto the heatingfsurface, and in the midst of steam previously generated,as distinguished from steam boilers which contain a body of watersufficient to cover the heating surface.

One of the leading objections to the introduction of that class of steamgenerators to which our inventionv relates has been the want ofdurability due to the deteriorating influence of unequal heat. Inordinary steam boilers the whole of the heating surface is covered withwater, which by circulation rapidly carries oi the heat and maintains anearly uniform temperaturej but as the heating surface in that class ofgenerators to'which our invention relates is not covered with water, andthe water is only introduced in small quantities, that portion of thesurface directly acted upon by the re becomes overheated,'and is therebyunduly expanded and much more expanded than the parts remote from thefire. This unequal expansion, and consequent unequal contraction, soondestroy the generator. l

' This serious objection we avoid by giving a rotary motion to thegenerator so as to heat every part of its' circumference to an equaltemperature, and so connecting it with the means for introducing thewater that every part of its surface performs an equal portion of dutyin generating steam, so that we avoid the overheating ot any one part ofthe surface, prevent unequal expansion and contraction, and theresulting rapid deterioration, whilst at the same time we are enabled togenerate a given amount of steam with considerably In the accompanyingdrawings, a represents 'the generator, which is a--hollow cylindricalvessel with concave-convex heads provided with hollow journals b badapted to turn in suitable boxes in the end walls c e of a furnace, d.ABy preference this furnace surrounds the generator, is provided with afire-grate, e, below the` generator, and has a 'lue space,f, at topleading to the chimney, soA that the products of combustion pass allaround the generator before escaping. Outsidethe furnace one of thejournals b is provided with a large spuru'heel, g, which is engaged by apinion, 71., on a shaft, 1,', which may derive motion for rotatingthegeneratorv either from the main engine, if the generator be used togenerate steam for drivingan engine, or from a small` pumping engine, orfrom any other motor. Andjvc deem it best, when the generator is to-beused for driving an` engine, to arrange theshaft of the pinion, inmanner well known t-o machinists, so that it can be turned by hand whenfirst firing up, and until the main or an auxiliary engine is started bythe steam generated. To the outer end oi' each journal are securedcylindrical steam pipes, j and 7c, so that both rotate with thegenerator, and they pass through and rotate in steam chests, l and 7n,provided wit-h stalling-boxes n, n and o 0' to prevent the escape ofsteam, the said pipes being pierced with holes for the discharge ofsteam into the steam chests. The steam generated for use is to be takenfrom the chest Z by a suitable pipe or pipes, and the chest mis to beconnected with the apparatus which 'is to regulate and control thesupply of water to be introduced into t-he generator. To the outer cndof the steam pipe c is secured a stuffing-box, p, through which passesthc watersupply pipe q from the apparatus that supplies the water, whichsaid .supply pipe is stationary, and the stealn pipe with thestuiiing-box 'rotates on it, vtho studng-box preventing the escape ofsteam. This water pipe q extends into the generator, and is providedwith branch pipes r which extend nearly to the upper part of thegenerator, where they are pierced with small holes for the discharge ofthe water in numerous small jets.r The inner end of the said water pipeg is closed, and by preference secured to thc closed end of a blow-offpipe, s, which extends centrally through the other steam pipe, j, andthroughfa stuffing-box, t, which closes the outer end of the said steampipe. The inner end of this blowfo" pipe curves down so that itsreceiviilg end reaches nearly to the'bottom of the generator, so thatany water that accumulates near the bottoni can forced out sensa, 2

by the pressure of steam, the outer end of the said pipe being providedin the usual manner with a blow-oli cock for this purpose.

From the foregoing it will be seen that as the generator rotates, andthe water-supplying pipes are station ary, the heating effect of theheat of the furnace, and the cooling effect of the water, must exercisean equal infiuence on every part of the circumference, and hence thatevery part of the surface of the generator, so organized, will beequally eiicient in generating steam, thus avoiding` the defectsheretofore found in this class of generators. And although we prefer tohave two steam pipes and two stealn chests, the one to supply the steamto theplace where it is to beused, and the other to supply steam to theapparatus which is to regulate and control the injection of the water,that in our belief being the preferable mode of application,`nevertheless one of these steam pipes and chests may be dispensed with,and the steam taken from the one chest for the4 several purposesrequired. And whenso modified the blow-ofi` pipe can pass through astuiiing-box at 4thc outer end of the journal. And -it will be obviousto engineers that any number of such generators may be used inconnection by connecting the steam chests of the several generators withone common steam chest, and in like manner regulating and controllingthe supply of one to thc several generators by the steam taken from asteam chest common to all, or from the steam chest of each, at the willof the constructor.

What we claim as our invention, and desire to secure by Letters Patent,is-

The generator mounted so as to rotate on, a horizontal or nearlyhorizontal axis and within a furnace, substantially as described, incombination With'the pipe or pipes for supplying andjetting the water,substantially as and for the purpose set forth.

We also claim the combination of the generator rotating within thefurnace, the steam pipe and steam chest, and -the pipe for supplying andjetting the waterivithin the generator, substantially as and' for thepurpose set'forth. i 1 i We also claim the combination of the generatorrotating within the furnace, the pipe for supplying and jetting thewater, the steam pipe and steam chest, and the blow-off pipe,substantially as and for the purpose set forth.

We alsoA claim the steam pipe attached'to and rotating with thegenerator, and provided with apertures, when combined with the steamchest and stuffing-box, so that Whilst rotating it will discharge thesteam into the stationary chest, substantially' as and for the purposeSet forth.

THOMAS MITCHELL, THOMAS H. MITCHELL.

Witnesses:

I. K. BOULwAai-s, W. S. KELLr.

